1. Technical Field
This disclosure relates to an apparatus and a method for providing an accurate image of a target object in a fluid-carrying pipe and more particularly, to an apparatus and method for providing an accurate image of a target object in an exploration or production well or in a pipeline carrying fluids such as hydrocarbons or aqueous liquids, and provides the opportunity of accurately determining which types of material said target object is composed of.
2. Description of the Related Art
For purposes of this disclosure, the term “fluid” is defined as any form of liquid and/or gas, separately or mixed. For purposes of this disclosure, the term “see” or “seeing” is defined as making image recordings that can be viewed by the human eye immediately or at a later stage, using, for example, a viewing screen.
The environment in exploration and production wells for oil and gas generally prohibits the use of video cameras due to the presence of saline solutions, mud, hydrocarbons and other substances that prevent the passage of visible light. Consequently, the possibility of seeing in such an environment by using a video camera is highly limited, due to the normal mixture of substances in the well. This very often results in time-consuming and costly inspections of well formations and equipment, and also fishing operations directed at the removal of unwanted objects in exploration and production wells.
Currently there exists no apparatus capable of seeing the targets under such conditions. However, the possibility of seeing in such environments is highly advantageous in terms of fulfilling the requirements for identification and localization of possible material damage and/or undesirable objects that have been lost or are stuck in the borehole.
U.S. Pat. No. 6,078,867 describes a system that produces a three-dimensional image of a borehole by means of a four-armed (or more) downhole caliper and gamma rays.
U.S. Pat. No. 4,847,814 describes a system for creating three-dimensional images by using data from a scan of a borehole carried out by use of a rotary acoustic transducer.
EP 1070970 describes a method of three-dimensional reconstruction of a physical quantity from a borehole comprising the creation of a three-dimensional image by measuring a first physical quantity as a function of depth, then to be compared with a second item.
WO 9935490 describes an apparatus and a method of depicting a lined borehole by means of ultrasound.
U.S. Pat. No. 5,987,385 describes an acoustic logging tool for creating a peripheral image of a borehole or a well lining by means of ultrasound generated by several transmitters/receivers mounted substantially in the same plane in the end piece of a drill string.
U.S. Pat. No. 4,821,728 describes a three-dimensional imaging system for representation of objects scanned by ultrasound.
U.S. Pat. No. 3,564,251 describes the use of radioactive radiation to establish information about the distance from the apparatus to the surroundings, e.g. a well wall, by creating a radial graph centered on the center of the apparatus.
Available radiation types for imaging applications range from radio waves to visible light to gamma rays. The wavelength of long-wave radiation in the form of radio waves (>1×10−1 m) is too great to create focused images that fulfill the necessary requirements. Short-wave radiation in the form of gamma rays (<1×10−11 m) has a wavelength and an energy level that gives sufficient image quality, but unfortunately requires a radiation source in the form of a radioactive material, which is out of the question in the environment of exploration and productions wells for oil and gas.
Embodiments of the invention address these and other disadvantages of the conventional art.